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Crashtd420

A 521 in Massachusetts

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So I used to tow a two horse trailer in the 1970's, with a 521.   I live in Oregon, near Portland.  I have been as far south as Central Point, near Medford, as far north as Vancouver BC, as far east as Joseph, and as far west as Seaside.   Many trips were in the Columbia gorge.  

I am pretty sure I used WFO for longer than 12 seconds a few times towing the horse trailer.  

Yes, they were full sized horses you can ride.  Average weight, 1,000 to 1,200 pounds.  454 to 545 kilograms to you metric folks.

 

By the way, the Datsun was more reliable than full sized F-250 I also used to tow a horse trailer.

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1 hour ago, Crashtd420 said:

Well stroffgren I hope your right... I like the idea that I actually achieved 95hp.....

 

This is the response from the dyno shop...

"Yes, the rule of thumb is you would ideally like to use the 1:1 gear.  However, we also don’t want to see the pull take more than 2 seconds per 1000 RPM of wide open throttle.  I tried a short 4th gear pull and with  the level of HP you are at, the 4th gear pull is way to slow and puts too much stress on the motor.  Generally, this also generates a ton of heat and the engine loses power over the 3rd gear pull anyway.  So I think what you have is the most accurate results we can get."

 

And I'll leave that whole dyno conversation at that..... 

 

 

 

This is inline with what I was reading. I know one of the issues with Dynos is that even with fans, there isnt much air flow through the radiator like being out on the highway so I think that is part of why they want to keep the pulls shorter. Also they may have realized how you drive your truck/what you use it for and felt that a quicker 3rd gear pull better reflected how you drive it and the actual loads your engine receives.

 

57 minutes ago, datzenmike said:

I say bullshit to them. Who the hell hasn't held the throttle full open for more than 12 seconds. It's NEVER going to stress the engine. If you are merely looking to measure peak HP start the pull at 4K then. Now I suspect that they are inflating the output by using 3rd gear. 

 

Im not sure what the shop would have to gain by inflating his numbers... he wasn't paying them to tune it, just for them to drive it and report on the numbers his engine was making... also not sure I have ever held my 510 at full throttle for 12 seconds- in a 4-5 speed if you held it for that long you would be bouncing off the limiter if you have one... otherwise you would need to shift. I dont think I've even ever held my tacoma (auto) at full throttle that long... well barely 0-60 in the truck is ~7.7 so if we assume 0-75 we are probably close to 10.

 

 

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All I know is it will rev faster in third that forth. The dyno wheel is a known mass and how fast it is accelerated is worked out to how much torque was needed to do this. Dynos  can't measure HP they measure torque and using RPM in the equation, HP can be calculated. Perhaps the RPM is what governs the output. Obviously the engine does not make more HP in a different gear I was just thinking how it's measured could be fooled.

 

I can't believe that 2 seconds per 1,000 RPMs is the limit. Like I said who hasn't pulled away in 4th or 5th and floored it from 1,800 up to 4K. How long is that, half a minute? No way you will over heat in 12 seconds.   

 

 

 

 

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If you approach dyno tuning as a means for getting the most out of what you have built, then who cares about the numbers? Does it run the best it can in its current configuration? If yes, then consider the goal achieved.

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1 hour ago, Stoffregen Motorsports said:

If you approach dyno tuning as a means for getting the most out of what you have built, then who cares about the numbers? Does it run the best it can in its current configuration? If yes, then consider the goal achieved.

Well said....while I would have liked to know if the hp number is correct or not the bigger goal was to have a better understanding of my engine carburetor combo and I do believe I achieved that....

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Ive been driving the datsun everyday I can and it has been running good, just rolled 5000 miles... 

 

Got a bunch of pieces and parts in lately. .

 

20191004-134346.jpg

Hopes to add a pcv valve to my intake..

 

20191004-134557.jpg

20191015-165625.jpg

Oil filter relocation and a new o2....

 

20191015-165601.jpg

Bump stops for the front.....

 

Radio is next on the list I did manage to hang on to these from my wifes old car..

20191015-165702.jpg

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Top bump stops will simply bolt in vs the the pull through type....

 

I Didnt even realize there was a lower one at first.... 

What I did find was I couldnt find a replacement to fit though.....

 

What I decided was to use these....

20191015-170557.jpg

 

Unfortunately they dont fit in the stock hole.... but the stock hole is the perfect size to tap for a 3/8-16... then just thread the bump stop in.... 

 

20191015-170458.jpg

 

20191015-170702.jpg

 

I did install the lock nut on top but once it started engaging the nylon it was a bitch to tighten further.... I need to remove the shock to tighten better...

Of course after the fact I realized I could have used a lock washer and different nut.... my luck I'll need to remove the shock anyhow to remove the nut....

 

 

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Somehow forgot I ordered this.....

 

20191016-160104.jpg

 

20191016-160135.jpg

 

I still need to bolt it down into the bed...

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I was able to get the box bolted down this weekend.... 

Then I got my radio working.... so much nicer having radio and to know what time it is..... 

 

20191021-065518.jpg

 

I still need to do the speakers, for now I stole 2 surround sound speakers I had and just threw them on the floor....

 

20191021-065523.jpg

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Bro your dash is so busy...how do you keep track of what does what? 

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3 minutes ago, d.p said:

Bro your dash is so busy...how do you keep track of what does what? 

It's really not that bad.....

Cant be making it easy for a thief to steal....

The couple times I've had a mechanic drive it I only turn the master switch off and on .... the rest stay on... only if i leave the truck parked some where do i shut all the switches down and turn the battery disconnect off....

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1 hour ago, Crashtd420 said:

It's really not that bad.....

Cant be making it easy for a thief to steal....

The couple times I've had a mechanic drive it I only turn the master switch off and on .... the rest stay on... only if i leave the truck parked some where do i shut all the switches down and turn the battery disconnect off....


All I read was 

OmU4mp.gif

Excited to see what you do next!

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So even after I replaced the u joint I still felt I had a bit of vibration at highway speed..... 

I checked my pinion angle again, maybe correctly this time but I'm still not really sure what the hell I'm doing.....

 

Either way how I checked this time told me I should be shimming my carrier bearing up because the driveshaft from the transmission to the carrier was actual aiming down about 2 degrees.

Transmission, rear driveshaft and rear differential all read zero..... 

 

So I added a 1/2 inch spacer....

 

Now my transmission, center driveshaft and rear differential all read zero and the back driveshaft aims up 2 degrees from the differential to the carrier.....

 

And yes this was checked with all 4 tires on the ground..... 

 

I'm hoping I am right because this has been the only way it made sense to me..

Guess I'll find out heading to work tomorrow, hopefully I didn't make it worse.. 

 

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I definitely improved the vibration.....

Cant believe I put up with it this long....

 

I am gonna leave it like that for now.... I want to raise the front a 1/4 to a 1/2 inch this winter, I hit the fender if I enter my driveway too quick... so i might have to do this one more time....

 

 

 

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39 minutes ago, Crashtd420 said:

I definitely improved the vibration.....

Cant believe I put up with it this long....

 

I

 

 

 

That's exactly what I said when I did my 710!!! Got used to it and didn't miss it till it was gone, and what an improvement!!!!! All this time all I had to do was shim the springs!!!

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3 degrees is stock.  Rule of thumb is a 1/4" carrier bearning shim for every 1" lowered.

 

Your truck is look sweeet!

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A good enough rule but only if you want good enough. Better is a drive line angle measuring tool...

 

51Bd59rvYhL.jpg$12 on Amazon

 

Angle in = angle out.

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Just a starting point Mike, measuring angle is always the proper way to set pinion angle.

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10 hours ago, datzenmike said:

A good enough rule but only if you want good enough. Better is a drive line angle measuring tool...

 

51Bd59rvYhL.jpg$12 on Amazon

 

Angle in = angle out.

This is what I was using....

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8 hours ago, Charlie69 said:

Just a starting point Mike, measuring angle is always the proper way to set pinion angle.

 

Actually close is good. I used a protractor and a string with a washer on it for a plumb bob. It's only as close as a string's width. Literally splitting hairs. If there's a next time I'll be getting the gauge.

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12 hours ago, Charlie69 said:

3 degrees is stock.  Rule of thumb is a 1/4" carrier bearning shim for every 1" lowered.

 

Your truck is look sweeet!

 

I'll probably add an extra degree and see if it makes it even better.....

 

Couple things to note is I'm using a Volvo carrier bearing on my driveshaft and because of the rake of the truck I shimmed the transmission mount to level the carburetor ....

So I have more than the normal stuff to think about.....

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All Datsun engines are tilted down to the rear.  

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Just now, datzenmike said:

All Datsun engines are tilted down to the rear.  

But what about the carburetor?

With the side draft I was reading somewhere about keeping it level?

 

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I don't think it would affect a float chamber much. It's only what 2" deep front to back.

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I guess I can look into that a bit more....

If I raise the front up like I intend that will create a slight tilt toward the back.....

 

 

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